The invention relates to a rotary fluid pump of a non-lubrication type in which fluid intake, compression and discharge operations are carried out by movement of vanes accompanied by the rotation of a rotor. More specifically, the present invention relates to a type thereof wherein a pair of resilient sealing plates are sealingly disposed each between a main body of a stator housing and an end head to defined end chambers each between the sealing plate and a recessed portion of the end head.
Vanes made of carbon materials or synthetic resin materials have previously been known in rotary fluid pumps of the non-lubrication type. Wear particles released from the vanes are generated by the sliding contact between the radially outer end portions of the vanes and an inner peripheral surface of the main body such as the sealing plates. In pumps of this type, provision must be made to prevent wear caused by the released wear particles. Conventionally, almost all of these wear particles are discharged to the outside of the pump through an outlet port formed in the main body. Wear particles released from the vanes are also generated by sliding contact between the end faces of the vanes and the inner surfaces of the sealing plates. Conventionally, such wear particles are discharged outside of the pump through at least one discharge port formed in the lower portion of the end chambers as disclosed in Japanese Utility Model Application No. 8823/1978. However, these techniques are not considered to be sufficient for totally discharging wear particles.
Further, in case such rotary fluid pump is utilized on an automobile, when the automobile travels over a rough road, dust or water may enter the pump through the discharge port thereby giving rise to additional wear between the inner surface of the sealing plates and the side faces of the rotor further degrading pumping efficiency. If the discharge port is closed to prevent dust and water from entering the pump, wear particles cannot then be discharged to the outside of the pump. Further, grease may flow from around the pump's bearings upon the closure of the discharge port. The above-noted difficulties need to be solved in order to provide improved pump performance and lifetime.